Generally for the bottom configuration of a so-called positive pressure can in which a carbonated drink like beer is sealingly contained, there has so far been a structure used, in which a central area accounting for most of the bottom is domed in such a way as to make its way into the can bottle, and ring-form bumps are joined to the outer periphery of the dome to provide a surface on which the bottom is to sit.
In such a general, conventional positive pressure can, the central portion of the bottom is domed in such a way as to make its way into the can bottle as described above, and the thickness of the bottom is set by far larger than that of the can shank forming the side wall of the can bottle.
Such positive pressure cans are now used on a huge market scale; so if the metal used for individual cans are able to be saved just a bit, it would end up with some considerable overall cost cuttings.
From such a point of view, Japanese Translation of PCT International Application Publication No. JP-T 2002-515842 shows that for the main purpose of reducing the thickness of the metal material of a can bottom wall, there is a bottom wall provided, in which an outwardly convex dome is provided, and a plurality of support legs, each of a substantially truncated quadrangular shape, are formed on that dome, and alternately located at spaces in a circumferential direction, extending down from the dome.
However, that publication discloses nothing about teachings enough to make sure resisting pressure and the freestanding capability of the can bottle: only with what is disclosed in that publication, there is a risk that even when the central area of the bottom bulges only a bit as the internal pressure rises, the freestanding capability of the can bottle may possibly be lost.
The situations being like this, the first idea (aspect) of the invention has for its object to provide a can bottle having a bottom that enables its rigidity to be maintained even when the bottom is made thin, and make sure the freestanding capability of the can bottle as the internal pressure rises, and a soft or hard drink can product using that can bottle.
The second idea (aspect) of the invention is an improvement in the first aspect of the invention, having for its objet to provide a can bottle having a bottom configuration capable of increasing buckling strength to vertical loads, and a soft or hard drink can product using that can bottle. To put it another way, a problem with a metal can having a so-called petaloid bottom configuration is that when there is a vertical load applied in the axial direction of the can bottle, the legs slip down toward the central portion of the bottom, deforming and starting to buckle up. The main purpose of the second aspect of the invention is to provide a solution to that problem.